docs: def _get_origcache(self, graph, dest, branch, turn, tick, *, forward):
          """Return a set of origin nodes leading to ``dest``"""
          origcache, origcache_lru, get_keycachelike, predecessors, adds_dels_sucpred = self._get_origcache_stuff
          lru_append(origcache, origcache_lru, ((graph, dest, branch), turn, tick), KEYCACHE_MAXSIZE)
          return get_keycachelike(
              origcache, predecessors, adds_dels_sucpred, (graph, dest),
              branch, turn, tick, forward=forward
          )